3D Bone Motion Reconstruction Using IMUs and Curve Interpolation
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Solution Overview
Problem
Current medical imaging devices are inadequate for analyzing posture and movement in three dimensions in real-time, are bulky, expensive, and not accessible to a wide audience, failing to meet the needs of healthcare professionals and patients for efficient, intuitive, and cost-effective monitoring and coaching during rehabilitation and physiotherapy.
Innovation Solution
A device using inertial measurement units placed on selected points of the body to measure rotation velocities, with processing units to generate a sequence of 3D images of moving bone elements, allowing real-time analysis and interpolation to reduce data volume, and incorporating a synchronization system for sensor alignment and drift correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multi-camera systems are used for 3D movement analysis, then measurement precision and analysis capability are improved, but device complexity, cost, and bulk increase significantly
Solution Approach 1:
The patent replaces the mechanical/optical camera-based measurement system with an inertial measurement unit (IMU) based system. Each IMU contains accelerometers and gyroscopes that directly measure linear accelerations and angular velocities, eliminating the need for complex camera arrays while achieving comparable or superior measurement precision for 3D movement analysis.
Solution Approach 2:
The system divides the measurement function into multiple independent IMU units distributed across the body segments being studied. Each IMU independently measures local motion parameters, and the central processing unit integrates these segmented measurements to reconstruct comprehensive 3D movement patterns, reducing individual unit complexity while maintaining overall system precision.
2Ease of manufacture
If inertial measurement units are used to reduce device complexity and cost, then ease of manufacture and accessibility are improved, but measurement precision and 3D analysis capability deteriorate
Solution Approach 1:
The patent combines multiple measurement functions (linear acceleration sensing, angular velocity sensing, and temporal synchronization) into integrated IMU units. By merging these functions into compact modules that can be manufactured using standard semiconductor processes, the system achieves both ease of manufacture and high measurement precision simultaneously.
Solution Approach 2:
The system incorporates real-time feedback through continuous data acquisition and processing from multiple IMUs. The central unit synchronizes measurements across all sensors and applies correction algorithms based on measured motion dynamics, improving precision through feedback-based error compensation while maintaining affordable hardware requirements.
3Measurement precision
If comprehensive movement data is collected to ensure analysis accuracy, then measurement precision is improved, but data volume and processing time increase
Solution Approach 1:
The patent performs preliminary data processing and filtering at the sensor level and during data acquisition. Raw acceleration and angular velocity data are pre-integrated to calculate positions and orientations, and preliminary noise filtering is applied before full analysis, reducing the computational burden on the central processing unit and decreasing overall processing time while maintaining precision.
4Productivity
If real-time analysis is implemented to provide immediate feedback, then productivity and coaching effectiveness are improved, but use of energy and computational resources increase
Solution Approach 1:
The system implements periodic data sampling and processing at optimized intervals rather than continuous processing. IMUs collect data continuously at high frequency, but the central unit processes information in periodic batches synchronized with movement phases or at fixed time intervals, providing real-time feedback capability while reducing average energy consumption through pulsed computational activity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables real-time, 3D analysis of posture and movement, reducing data volume and cost, and providing a user-friendly, accessible tool for monitoring and coaching exercises, suitable for medical practice.
Implementation Method 1
a plurality of inertial measurement units, each inertial measurement unit being configured to cyclically measure linear accelerations on three axes and velocities of rotation about these three axes
Data Source
AI summary
A device for generating a sequence of images configured to represent in 3D a continuous series of aligned moving bone elements belonging to a subject. The device includes a plurality of inertial units intended to be arranged facing a plurality of measuring points, chosen by a practitioner, on the continuous series of aligned bone elements of the subject to cyclically take measurements. It also includes at least one first treatment unit configured to receive the measurement data from the respective inertial units and transform them into orientations of the inertial units. The device further includes a second treatment unit configured to receive the orientations of the inertial units; to update the orientations and the positions of the measuring points facing the inertial units on the basis of the orientations of the inertial units as and when the second treatment unit receives them; and then to form a curve representing the continuous series of bone elements using the positions of the thus-obtained measuring points and the interpolations between the positions of the measuring points. The second treatment unit is configured to allow the practitioner to input anatomical data or observation data used to correct the curve. The device is used to reconstruct a realistic image of a continuous series of aligned moving bone elements on the basis of a minimum amount of data. The device is used to establish reliable diagnoses from the obtained images and remotely assist a patient with exercises.